The present invention relates, in general, to a bumper structure for a motor vehicle.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
A bumper structure is mounted to the front or rear of a motor vehicle and includes a bumper cross member to transmit impact forces, generated in the event of a collision, into crash boxes which are arranged at the ends of side rails of the motor vehicle. In this way, impact energy is converted locally in the crash boxes into deformation energy. In current crash repair tests, a vehicle is moved against a barrier with slight overlap at low speed. As a consequence of the relatively slight overlap, it is desired to keep away any damage from the side of the motor vehicle that has not hit the obstacle in order to avoid repair work and for insurance reasons. The same holds true for the impact-distal crash box on the unaffected side.
Crash boxes may be connected in one spot or several spots to the cross member. A multi-point attachment is disclosed, e.g., in European Pat. Publ. No. EP 1 234 729 and International Publ. No. WO 2004/113131. Examples of a single-point attachment include German Offenlegungsschrift DE 102 34 045 A1 and German Offenlegungsschrift DE 199 07 783 A1. Single-point attachments with oblong holes are disclosed in European Pat. Publ. No. EP 1 604 869 A1 or French Pat. No. FR 2 506 700. Japanese Pat. No. JP 08 216 808 A discloses the provision of guide elements in an area of attachment of the bumper cross member. German Offenlegungsschrift DE 2 162 412 A discloses a movable support of the bumper cross member in relation to the vehicle body via pivot arms.
However, for a number of reasons, the various proposals are endowed with drawbacks and shortcomings because the attachment area of the crash box that is not part in an actual collision becomes destroyed and thus must be replaced.
It would therefore be desirable and advantageous to provide an improved bumper structure to obviate prior art shortcomings and to prevent damage to a crash box that is distal to the crash site.